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Star designation

Star designation

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Designations of star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...

s
(and other celestial bodies) are done by the International Astronomical Union
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...

 (IAU). Many of the star names in use today were inherited from the time before the IAU existed. Other names, mainly for variable stars (including nova
Nova
A nova is a cataclysmic nuclear explosion in a star caused by the accretion of hydrogen on to the surface of a white dwarf star, which ignites and starts nuclear fusion in a runaway manner...

e and supernova
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...

e), are being added all the time.

Approximately 10,000 stars are visible to the naked eye
Naked eye
The naked eye is a figure of speech referring to human visual perception unaided by a magnifying or light-collecting optical device, such as a telescope or microscope. Vision corrected to normal acuity using corrective lenses is considered "naked"...

. Pre-modern catalogues listed only the brightest of these. Hipparchus
Hipparchus
Hipparchus, the common Latinization of the Greek Hipparkhos, can mean:* Hipparchus, the ancient Greek astronomer** Hipparchic cycle, an astronomical cycle he created** Hipparchus , a lunar crater named in his honour...

 in the 2nd century BC enumerated about 850 stars. Johann Bayer
Johann Bayer
Johann Bayer was a German lawyer and uranographer . He was born in Rain, Bavaria, in 1572. He began his study of philosophy in Ingolstadt in 1592, and moved later to Augsburg to begin work as a lawyer. He grew interested in astronomy during his time in Augsburg...

 in 1603 listed about twice this number. Only a minority of these have proper names, all others are designated by catalogization schemes.
Only in the 19th century did star catalogues list the naked-eye stars exhaustively.
The most voluminous modern catalogues list of the order of a billion stars, out of an estimated total of 200 to 400 billion in the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...

.

Proper names



Several hundred of the brightest stars have traditional names, most of which derive from Arabic
Arabic language
Arabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book...

, but a few from Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

.

There are a number of problems with these names, however:
  • Spellings are often not standardized (Almach
    Gamma Andromedae
    Gamma Andromedae is the third brightest star in the constellation of Andromeda. It is also known by the traditional name Almach , from the Arabic العناق الأرض al-‘anāq al-’arđ̧ "the caracal" .Another term for this star used by medieval astronomers...

     or Almaach or Almak or Alamak)
  • Many stars have more than one name of roughly equal popularity (Mirfak
    Alpha Persei
    Alpha Persei is the brightest star in the constellation of Perseus, just outshining the constellation's best known star Algol. It also bears the traditional names Mirfak and Algenib...

     or Algenib or Alcheb; Regor
    Gamma Velorum
    Gamma Velorum is a star system in the constellation Vela. At magnitude +1.7, it is one of the brightest stars in the night sky. It has the traditional names Suhail and Suhail al Muhlif, which confusingly also apply to Lambda Velorum...

     or Suhail al Muhlif; Alkaid
    Eta Ursae Majoris
    Eta Ursae Majoris is a star in the constellation Ursa Major. It has the traditional names Alkaid and Benetnash ....

     or Benetnasch; Gemma or Alphecca; Alpheratz
    Alpha Andromedae
    Alpha Andromedae , which has the traditional names Alpheratz and Sirrah , is the brightest star in the constellation of Andromeda. Located immediately northeast of the constellation of Pegasus, it is the northeastern star of the Great Square of Pegasus...

     and Sirrah)
  • Because of imprecision in old star catalogs, it may not be clear exactly which star within a constellation a particular name corresponds to (e.g., Alniyat, Chara).
  • Some stars in entirely different constellations may have the same name: Algenib in Perseus
    Alpha Persei
    Alpha Persei is the brightest star in the constellation of Perseus, just outshining the constellation's best known star Algol. It also bears the traditional names Mirfak and Algenib...

     and Algenib in Pegasus
    Gamma Pegasi
    Gamma Pegasi is a star in the constellation of Pegasus. It also has the traditional name Algenib; confusingly however, this name is also used for Alpha Persei....

    ; Gienah in Cygnus and Gienah in Corvus, Alnair in Grus
    Alpha Gruis
    Alpha Gruis is the brightest star in the constellation Grus.Alpha Gruis has a proper name Alnair or Al Nair , came from the Arabic al-nayyir [an-nai:r], meaning "the bright one"...

     and Alnair in Centaurus
    Zeta Centauri
    Zeta Centauri is a star in the constellation Centaurus. It has the proper name Alnair, from the scientific-Arabic Nayyir Badan Qanṭūris , meaning "The Bright of the Body of the Centaur"....

    .


In practice, the traditional names are only universally used for the very brightest stars (Sirius
Sirius
Sirius is the brightest star in the night sky. With a visual apparent magnitude of −1.46, it is almost twice as bright as Canopus, the next brightest star. The name "Sirius" is derived from the Ancient Greek: Seirios . The star has the Bayer designation Alpha Canis Majoris...

, Arcturus, Vega
Vega
Vega is the brightest star in the constellation Lyra, the fifth brightest star in the night sky and the second brightest star in the northern celestial hemisphere, after Arcturus...

, etc.) and for a small number of slightly less bright but "interesting" stars (Algol, Polaris
Polaris
Polaris |Alpha]] Ursae Minoris, commonly North Star or Pole Star, also Lodestar) is the brightest star in the constellation Ursa Minor. It is very close to the north celestial pole, making it the current northern pole star....

, Mira
Mira
Mira also known as Omicron Ceti , is a red giant star estimated 200-400 light years away in the constellation Cetus. Mira is a binary star, consisting of the red giant Mira A along with Mira B. Mira A is also an oscillating variable star and was the first non-supernova variable star discovered,...

, etc.). For other naked eye stars, the Bayer designation
Bayer designation
A Bayer designation is a stellar designation in which a specific star is identified by a Greek letter, followed by the genitive form of its parent constellation's Latin name...

 is often preferred.

In addition to the traditional names, a small number of stars that are "interesting" can have modern English
English language
English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...

 names. For instance Barnard's star
Barnard's star
Barnard's Star, also known occasionally as Barnard's "Runaway" Star, is a very low-mass red dwarf star approximately six light-years away from Earth in the constellation of Ophiuchus . In 1916, the American astronomer E.E...

 has the highest known proper motion
Proper motion
The proper motion of a star is its angular change in position over time as seen from the center of mass of the solar system. It is measured in seconds of arc per year, arcsec/yr, where 3600 arcseconds equal one degree. This contrasts with radial velocity, which is the time rate of change in...

 of any star and is thus notable even though it is far too faint to be seen with the naked eye. See stars named after people
Stars named after people
Over the past few centuries, a small number of stars have been named after individual people. It is common in astronomy for objects to be given names, in accordance with accepted astronomical naming conventions...

.

Two second-magnitude stars, Alpha Pavonis
Alpha Pavonis
Alpha Pavonis is a star in the constellation Pavo. It is also known by the name Peacock, which was assigned by Her Majesty's Nautical Almanac Office in the late 1930s during the creation of the Air Almanac, a navigational almanac for the Royal Air Force...

 and Epsilon Carinae
Epsilon Carinae
Epsilon Carinae is a star in the constellation Carina. At apparent magnitude +1.86 it is one of the brightest stars in the night sky, but is not visible from the northern hemisphere....

, were assigned the proper names Peacock and Avior respectively in 1937 by Her Majesty's Nautical Almanac Office during the creation of The Air Almanac, a navigational almanac for the Royal Air Force
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

. Of the fifty-seven stars included in the new almanac, these two had no classical names. The RAF insisted that all of the stars must have names, so new names were invented for them.

The book Star Names: Their Lore and Meaning
Star Names: Their Lore and Meaning
Star Names: Their Lore and Meaning is a book by Richard Hinckley Allen, published in 1899.It discusses the names of stars and constellations and their origin.-Author:...

by R.H.Allen (1899) has had effects on star names:
  • It lists many Assyrian/Babylonian
    Akkadian language
    Akkadian is an extinct Semitic language that was spoken in ancient Mesopotamia. The earliest attested Semitic language, it used the cuneiform writing system derived ultimately from ancient Sumerian, an unrelated language isolate...

     and Sumer
    Sumer
    Sumer was a civilization and historical region in southern Mesopotamia, modern Iraq during the Chalcolithic and Early Bronze Age....

    ian star names recovered by archaeology
    Archaeology
    Archaeology, or archeology , is the study of human society, primarily through the recovery and analysis of the material culture and environmental data that they have left behind, which includes artifacts, architecture, biofacts and cultural landscapes...

    , and some of these (e.g. Sargas and Nunki) have come into general use.
  • It lists many Chinese
    China
    Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

     star names, and some of these (e.g. Cih alias Tsih) have come into general usage.
  • R.H.Allen represented the "kh" sound by `h' with a dot above, and at least one astronomy book (a book by Patrick Moore
    Patrick Moore
    Sir Patrick Alfred Caldwell-Moore, CBE, FRS, FRAS is a British amateur astronomer who has attained prominent status in astronomy as a writer, researcher, radio commentator and television presenter of the subject, and who is credited as having done more than any other person to raise the profile of...

    ) using R.H.Allen as a source, has misread this unfamiliar letter as `li'.


A few stars are named for individuals
Stars named after people
Over the past few centuries, a small number of stars have been named after individual people. It is common in astronomy for objects to be given names, in accordance with accepted astronomical naming conventions...

. These are mostly unofficial names that became official at some juncture.
The first such case (discounting characters from Greek mythology) was Cor Caroli
Cor Caroli
Cor Caroli is the brightest star in the northern constellation Canes Venatici...

 (α CVn), named in the 17th century for Charles I of England
Charles I of England
Charles I was King of England, King of Scotland, and King of Ireland from 27 March 1625 until his execution in 1649. Charles engaged in a struggle for power with the Parliament of England, attempting to obtain royal revenue whilst Parliament sought to curb his Royal prerogative which Charles...

. The remaining examples are mostly stars named after astronomers or astronauts.

Catalogue numbers


In the absence of any better means of designating a star, catalogue numbers are generally used. A great many different star catalogues are used for this purpose, see star catalogue
Star catalogue
A star catalogue, or star catalog, is an astronomical catalogue that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the years, and this article covers only some...

s.

By constellation


The first modern schemes for designating stars systematically labelled them within their constellation.
  • The Bayer designation
    Bayer designation
    A Bayer designation is a stellar designation in which a specific star is identified by a Greek letter, followed by the genitive form of its parent constellation's Latin name...

     is such a system, published by Johann Bayer
    Johann Bayer
    Johann Bayer was a German lawyer and uranographer . He was born in Rain, Bavaria, in 1572. He began his study of philosophy in Ingolstadt in 1592, and moved later to Augsburg to begin work as a lawyer. He grew interested in astronomy during his time in Augsburg...

     in 1603. It introduced a system of designating the brightest stars in each constellation by means of Greek (or less often Latin) letters, and is still widely used. The original list of Bayer designations contained 1,564 naked-eye stars.
  • The Flamsteed designation
    Flamsteed designation
    Flamsteed designations for stars are similar to Bayer designations, except that they use numbers instead of Greek letters. Each star is assigned a number and the Latin genitive of the constellation it lies in...

     uses the same approach, using numbers rather than letters. Published in 1712 (without the consent of the author, John Flamsteed
    John Flamsteed
    Sir John Flamsteed FRS was an English astronomer and the first Astronomer Royal. He catalogued over 3000 stars.- Life :Flamsteed was born in Denby, Derbyshire, England, the only son of Stephen Flamsteed...

    ), it lists 2,554 stars.
  • The Gould designation
    Gould designation
    Gould designations for stars are similar to Flamsteed designations in the way that they number stars within a constellation in increasing order of right ascension. Each star is assigned an integer , followed by " G. " , and then the Latin genitive of the constellation it lies in...

     by Benjamin Gould (1879) also lists stars by constellation, but numbers them by increasing order of right ascension.
  • Hevelius and Bode
    Bode
    Bode may refer to:in people by surname:*Boyd Henry Bode , American academic and philosopher*Bruce Bode, MD, FACE, American diabetes specialist*Denise Bode , American politician*Erin Bode, American singer...

     both numbered stars within constellations similarly. Their number systems has fallen out of use, but their designations even now are occasionally mistakenly treated as Flamsteed designations. 47 Tucanae
    47 Tucanae
    47 Tucanae or just 47 Tuc is a globular cluster located in the constellation Tucana. It is about 16,700 light years away from Earth, and 120 light years across. It can be seen with the naked eye, with a visual magnitude of 4.0...

    , a number assigned by Bode, is a famous example.

Full-sky catalogues


Full-sky star catalogues detach the star designation from the star's constellation and aim at enumerating all stars with apparent magnitude greater than a given value.
  • the Histoire Céleste Française
    Histoire Céleste Française
    Histoire Céleste Française is an astrometric star catalogue published in 1801 by the French astronomer Jérôme Lalande and his staff at the Paris Observatory. This star catalog consists of the locations and apparent magnitudes of 47,390 stars, up to magnitude 9...

    (1801) enumerated 47,390 stars to magnitude 9.
  • the Bonner Durchmusterung (1859) was the most complete star catalogue compiled without the aid of photography. It listed a total of 320,000 northern stars, expanded by the Cordoba Durchmusterung (1892) and the Cape Photographic Durchmusterung (1896).
  • the Henry Draper Catalogue
    Henry Draper Catalogue
    The Henry Draper Catalogue is an astronomical star catalogue published between 1918 and 1924, giving spectroscopic classifications for 225,300 stars; it was later expanded by the Henry Draper Extension , published between 1925 and 1936, which gave classifications for 46,850 more stars, and by the...

    (1924) listed 225,300 stars to magnitude 10, extended to a total of 359,083 in 1949. The HD numbers remain in widespread use for stars that do not have a Flamsteed or Bayer designation.
  • the Bright Star Catalogue
    Bright Star Catalogue
    The Bright Star Catalogue, also known as the Yale Catalogue of Bright Stars or Yale Bright Star Catalogue, is a star catalogue that lists all stars of stellar magnitude 6.5 or brighter, which is roughly every star visible to the naked eye from Earth. It is currently available online in its 5th...

    of 1930 listed all stars brighter than magnitude 6. It was supplemented to include stars down to magnitude 7.1 in 1983.
  • the Catalogue astrographique was compiled between 1891 and 1950 with the aim of listing all stars to magnitude 11, resulting in a list of 4.6 million stars. It is under continued development, now under custody of the U.S. Naval Observatory.
  • the USNO-B1.0 catalogue contains over a billion objects, and is also under continued development at the U.S. Naval Observatory.
  • the online Guide Star Catalog II
    Guide Star Catalog
    The Guide Star Catalog is also known as the Hubble Space Telescope, Guide Catalog . It is a star catalog compiled to support the Hubble Space Telescope with targeting off-axis stars. GSC-I contained approximately 20,000,000 stars with apparent magnitudes of 6 to 15. GSC-II contains 945,592,683...

    (2008) contains 945 million stars to magnitude 21.

Variable designations



Variable stars which do not have Bayer designations are given special designations which mark them out as variable stars.

Exoplanet searches


When a planet is detected around a star, the star is often given a name and number based on the name of the telescope or survey mission that discovered it and based on how many planets have already been discovered by that mission e.g. HAT-P-9
HAT-P-9
|- bgcolor="#FFFAFA"| Equatorial [ g ] || 201,21 m/s2HAT-P-9 is a magnitude 12 star approximately 1560 light years away in the constellation Auriga.-Planetary system:...

, WASP-1
WASP-1
WASP-1 is a metal rich magnitude 12 star located about 1240 light-years away in the Andromeda constellation.-Planetary system:In 2006 the extrasolar planet WASP-1b was discovered by the SuperWASP project using the transit method....

, COROT-1
COROT-1
COROT-1 is a yellow dwarf main sequence star similar to our Sun. The star is located approximately 1,560 light-years away in the constellation of Monoceros. The apparent magnitude of this star is 13.6, which means it is not visible to the naked eye; however, it can be seen through a medium sized...

, Kepler-4
Kepler-4
Kepler-4 is a sunlike star located about 1631 light-years away in the constellation Draco. It is in the field of view of the Kepler Mission, a NASA operation purposed with finding Earth-like planets. Kepler-4b, a Neptune-sized planet that orbits extremely close to its star, was discovered in its...

.

Sale of star names


There are a number of companies that sell naming rights to obscure stars for commemorative purposes. These sales of star names are unrelated to the official designations made by the IAU and the names are not recognised by any international scientific or registration body. As a result a single star can potentially named independently by multiple companies, or multiple times by the same company.

See also


External links